CHAPTER 3 Swine Manure Production and Nutrient Content John P. Chastain, James J. Camberato, John E. Albrecht, and Jesse Adams, III INTRODUCTION Knowledge of the amount of manure and plant nutrients produced on a swine farm is the first step in the proper operation of a swine manure handling, treatment, and utilization system. The nutrient and volatile solids content of swine manure will vary with the digestibility of the ration, animal age, amount of feed wasted, the amount of water wasted, and the amount of water used to remove manure from the building. The data provided in this chapter is to be used for general planning purposes. South Carolina regulations (Standards for the Permitting of Agricultural Animal Facilities: R.61-43) require swine producers to have manure samples analyzed annually to establish land application rates. MANURE PRODUCTION The quantity of fresh swine manure (including feces and urine) produced each day is shown in Table 3.1. The quantity of manure, total solids, and volatile solids produced per day are given per animal unit (AU). An animal unit is equal to 1,000 pounds of live animal weight. The quantity of manure produced is given in pounds (lb), cubic feet (ft3), and gallons (gal). The total and volatile solids content in swine manure is given in lb/AU/day since these are the units often used to size an anaerobic lagoon or digester (see chapter 4 for more details). The total solids content is the combination of the solids than can be broken down by bacteria and the solids that will never degrade. Volatile solids are the solids that can be decomposed by biological treatment. Table 3.1. Daily production of fresh manure, total solids, and volatile solids for typical swine farms ( adapted from MWPS-18, 1993; ASAE standard D384.1, 1998; and Barker, 1990). Average Manure Production Total Volatile Farm Weight per AU 1 Solids Solids 2 3 Type lb/PU lb/day ft /day gal/day lb/AU/day lb/AU/day Farrow-to-Wean 433/sow 60 0.97 7.26 5.9 4.5 Nursery 30/pig 84 1.35 10.1 11.0 8.5 Farrow-to-Feeder 522/sow 64 1.03 7.70 6.7 5.1 Feeder -to- Finish 135/hog 84 1.35 10.1 11.0 8.5 Farrow-to-Finish 1,417/sow 77 1.24 9.28 9.3 7.2 1 AU = 1,000 lb of live weight. 2 PU = production unit. The production unit is a sow, pig, or hog as shown. 3-1 CALCULATION OF AVERAGE PRODUCTION LIVE WEIGHT AND NUMBER OF ANIMAL UNITS The manure and solids production data are given as the pounds or volume per animal unit per day. The average production unit depends on the type of swine that are kept on the farm. For example, the production unit on a farrow-to-wean farm is the sow. The animal weight per sow includes the weight for all pigs produced, gestating and breeding sows, boars, and replacement animals. On a swine farm with only one type of animal, such as a feeder-to-finish farm, the average weight is simply the average weight of the hogs at any time. For example, if the average weight of a feeder pig that is placed in the building is 50 lb and the average weight of a market hog is 220 lb the average weight per hog is (50 + 220)/2 = 135 lb. Some of the facility and lagoon site selection requirements in the South Carolina regulations depend on the size of the operation. The average production live weight on the farm is used to define farm size. Swine operations with more than 420,000 pounds of average live weight fall under the regulations for large swine facilities. The values in Table 3.1 can be used to calculate the average production live weight using the following equation: Average Production Live Weight = Number of Production Units x (lb / PU). (3.1) Example 3.1 Determine the total average production live weight for a 1000 sow, farrow-to- feeder swine farm using equation 3.1. Is this farm subject to the regulations for large swine facilities? From Table 3.1 the average weight per PU for a farrow-to feeder farm is 522 lb/sow. The average production live weight for a 1,000 sow farm is: 1,000 sows x 522 lb/sow = 522,000 pounds. In the South Carolina regulations a large swine farm is defined as any farm that has a production live weight that is greater than 420,000 pounds. Therefore, a 1,000 sow, farrow-to- feeder farm comes under the regulations for large swine farms. Example 3.2 What is the largest farrow-to-feeder farm that does not come under the regulations for large swine facilities? Calculate the number of production units that will give an average live weight of 420,000 pounds as follows: 420,000 lb ÷ 522 lb/sow = 804.6 sows. Therefore, the largest number of sows that can be kept on a farrow-to-feeder farm and still come under the regulations for small swine facilities is 804 sows. The daily manure production data given in Table 3.1 is given per animal unit (AU). The number of animal units on a farm is calculated as: Number of Animal Units (No. AU) = Average Production Live Weight ÷ 1000. (3.2) 3-2 Example 3.3 Calculate the number of animal units for a 1,000 sow farrow-to-feeder farm. The average production live weight of a 1,000 sow farrow-to-feeder farm was calculated in example 1 and was found to be 522,000 pounds. The number of animal units is: 522,000 ÷ 1,000 = 522. MANURE VOLUMES FOR DIFFERENT MANURE HANDLING SYSTEMS The manure production data given in Table 3.1 is for undiluted manure as excreted from the animals. However, the actual volume that must be collected, handled, treated, and stored varies with the methods used to remove manure from the building. In addition, wasted water from waterers and building washdown can increase the manure volume by 10 to 30%. The volume of manure and wasted water is compared with the amount of liquid manure that flows from pit-recharge and flush buildings in Table 3.2. The manure and wasted water volumes in the table are good estimates of the volume of fresh manure, waterer wastage, and washdown water that is added to a manure handling system each day. This volume is used to calculate the manure storage volume when a lagoon or liquid storage structure is sized. In South Carolina, most swine facilities use a flush or pit-recharge system with a lagoon or storage pond (chapter 4). The water used to remove manure from a pit-recharge or flush building is typically recycled from the lagoon. Pit-recharge systems are gaining popularity over flush systems because less water volume is required to clean the building. Table 3.2. Variation of swine manure volume depending on type of manure handling system (to convert to gallons multiply ft3 by 7.48). Average Manure and Weight Wasted Water 1 Pit-Recharge 2 Flush 3 Farm Type lb/PU ft3/AU/day ft3/AU/day ft3/AU/day Farrow-to-Wean 433 lb 1.16 9.3 9.4 Nursery 30 lb 1.62 9.4 17.6 Farrow-to-Feeder 522 lb 1.24 9.4 10.7 Feeder -to- Finish 135 lb 1.62 6.8 17.6 Farrow-to-Finish 1,417 lb 1.49 7.8 14.9 1 Dilution water from waterer wastage and washdown was assumed to be 20% of the manure volume. Does not include water for flushing or pit-recharge. 2 Includes wasted water and water used to remove manure from buildings. Total solids content for pit- recharge systems varies from 1.5% to 2.6%. 3 Includes wasted water and water used to remove manure from buildings. Total solids for flush systems can vary from 0.5 to 2%. A value of 1% was used to calculate the volumes shown. The actual amount of manure handled per day on a given farm will vary with farm size and the type of manure handling system used. A flush system will remove manure from a building 4 to 3-3 12 times a day. A pit-recharge system is typically emptied every 5 to 7 days. These daily values can be used to estimate weekly or annual volumes once the manure removal schedule is established. Example 3.4 A feeder-to-finish swine farm has 6 pit-recharge buildings that are designed to house a maximum of 880 hogs. The manure from one building is emptied every 7 days. What is the volume of manure that must be handled by the waste system? Give the volume in cubic feet and gallons. Step 1. The average weight per PU for a feeder-to-finish farm is 135 lb/hog (Table 3.2). Calculate the number of animal units in a single building as: 880 x 135 lb/hog ÷ 1,000 lb/AU = 118.8 AU / building. Step 2. From Table 3.2, the total manure and wasted water produced per AU per day is 6.8 ft3/AU/day. Calculate the manure volume per day as follows: 118.8 AU/building x 6.8 ft3 / AU / day x 7 days = 5655 ft3 of manure/building. Step 3. The volume in gallons is 5655 ft3/day x 7.48 gal/ft3 = 42,299 gal/building. NUTRIENT CONTENT OF SWINE MANURE Swine manure contains all 13 of the essential plant nutrients that are used by plants.